1. Field of the Invention
The present invention relates to an X-ray diagnostic imaging apparatus. The present invention particularly relates to a technique for making it possible to pick up images of a human body or a subject under examination at accurate and a variety of image pick-up positions, for improving the operation of an operator, and for achieving a provision of a compact and simple structure of an X-ray diagnostic imaging apparatus, in diagnosing the subject based on an image obtained by irradiating radial rays such as X-rays, for example, onto the subject.
2. Description of the Background Art
An X-ray diagnostic imaging apparatus irradiates radiation such as X-rays, for example, onto a subject under examination, and detects a distribution of the radiation transmitted through the subject, thereby to pick up an image of a detected portion of the subject. As a supporting unit in this X-ray diagnostic imaging apparatus, there is a circulator supporting unit, for example.
FIG. 1 is a schematic view for showing a conventional X-ray diagnostic imaging apparatus. As shown in FIG. 1, in this X-ray diagnostic imaging apparatus, an X-ray generator 1 and an X-ray detector 503 are arranged to face each other on both ends of an arm 501, and they are supported in a fixed state. As shapes of the arm 501, there have been known two broad types of a C-type and a U-type. From the viewpoint of the efficiency of a three-dimensional positioning, the C-type as shown in FIG. 1 has been used as the main. The arm 501 is held slidably by a holder 502. The holder 502 is held rotatably around a main axis by a supporting pillar (not shown), and the supporting pillar is installed rotatably around the supporting pillar on the ceiling or on the floor. A supporting pillar of the type suspended from the ceiling has a rail fixed to the ceiling, and the supporting section can make a horizontal move in one direction or two directions along this rail.
As the X-ray detector 503, an image intensifier (hereinafter to be referred to as an I.I.) is employed. The X-ray detector 503 converts X-ray information of the X-rays transmitted through the subject 7 into optical information, and collects the optical information with an optical lens and takes it into a TV camera. The information taken into the TV camera is displayed as an image. The X-ray detector 503 can be moved by a moving mechanism to upward and downward directions with respect to the X-ray generator 1 shown in FIG. 1.
The above conventional X-ray diagnostic imaging apparatus, however, has had the following problems.
First, according to the conventional X-ray diagnostic imaging apparatus, articles of heavy weight, such as, for example, the I.I., the optical system mechanism, the X-ray detector 503 such as the TV camera, and the X-ray generator 1, are provided on both ends of the C-type arm 501. Accordingly, when the arm 501 having a large size and a heavy weight is rotated in a direction of the main axis, there is generated a large rotation inertia, making it difficult to fine tune a rotation angle of the arm 501. Therefore, it has been difficult to achieve a correct control of an image pick-up position intended by the operator.
Thus, in order to facilitate a fine-tuned control of an image pick-up position, it may be considered appropriate to reduce the size and weight of the X-ray detector 503, by using a solid detector formed by a plurality of solid image pick-up elements, in place of the I.I. However, when this solid detector is used, a weight balance between the X-ray detector and the X-ray generator 1 may be lost, and the rotation inertia moment may become substantially worse than the current situation, which makes it difficult to carry out the fine-tuned control.
On the other hand, in recent years, there have been made trials to obtain a three-dimensional image of a subject under examination by picking up images of the subject while rotating the C-type arm, and then by reconstructing projection images of the subject into a three-dimensional image. In order to reconstruct a three-dimensional image, it is necessary to obtain projection images of the subject corresponding to at least 180 degrees plus X-ray cone beam (or fan beam) angle. However, the conventional C-type arm 501 and the holder 502 have a limit to their slide strokes, and, therefore, it is difficult to obtain image information that can provide a three-dimensional reconstruction.
For collecting image information from the plurality of angles, according to the conventional X-ray diagnostic imaging apparatus, it is possible to rotate the C-type arm 501 around the main axis. However, in this case, in order to avoid an interference generated between the arm 501 and the subject 7 at the time of the rotation, there is no other way than to rotate the subject 7 around a body axis L of the subject by making an access to the subject 7 from a head side. This method has a limitation to an area of the subject 7 to which X-rays are irradiated and from which transmitted X-rays can be collected. In other words, as the conventional arm 501 access from the head side of the subject 7, a move of the arm 501 in the direction of the body axis L is limited to a range in which the head of the subject 7 and the arm 501 are not brought into contact with each other. Accordingly, it has been difficult to access to a lower body part of the subject 7, particularly, to an inguinal region, for example. As a result, it has been difficult to control image pick-up positions in various ways in line with an operator""s intention.
Further, as a large mechanism is required for the supporting unit for supporting the holder 502 and the arm 501 that are necessary for collecting the image of the main axis rotation, the conventional the X-ray diagnostic imaging apparatus has taken a large installation space, which interferes with the field of vision of an operator and interrupts his or her operation.
It is an object of the present invention to provide an X-ray diagnostic imaging apparatus capable of easily collecting images at accurate and a variety of image pick-up positions, by improving an access of an X-ray generator and an X-ray detector to a subject under examination.
It is another object of the present invention to provide an X-ray diagnostic imaging apparatus capable of improving the operation of an operator without interfering with the field of vision of the operator, through the reduction in size and weight of a supporting unit.
In order to achieve the above objects, a first aspect of the present invention provides, as shown in FIG. 2, an X-ray diagnostic imaging apparatus 100 for irradiating X-rays onto a subject under examination and picking up an image of the subject by detecting the X-rays transmitted through the subject, the X-ray diagnostic imaging apparatus comprising: an X-ray generator 1 for irradiating X-rays onto the subject; an X-ray detector 2 for taking in an X-ray image formed by the X-rays irradiated onto the subject and transmitted through the subject; an arm 3 extended from the X-ray generator 1 to make a detour around the subject, for holding the X-ray detector 2; and a holder 4 and 5 for movably holding the X-ray generator 1.
According to the above structure, the X-ray generator 1 and the detector 2 are formed integrally with the arm 3, and the X-ray generator 1 is held and driven by the holders 4 and 5. Accordingly, the arm 3 that holds the X-ray generator 1 and the detector 2 by itself does not require a driving mechanism. Further, it is not necessary to have a space for installing the mechanism for carrying out a main axis rotation. Thus, it is possible to provide a simpler and lighter-weight structure of the X-ray diagnostic imaging apparatus. Further, unlike the conventional apparatus, it is not necessary to take into consideration the maintenance of a balance between the X-ray generator and the detector and the rotation inertia generated during a rotation of the holder. Therefore, it becomes possible to accurately control an image pick-up position.
The X-ray generator 1 may be provided in the holders 4 and 5 so as to be rotatable with the X-ray irradiation direction as an axis. Further, the X-ray generator 1may also be provided so as to be slidable along the inner surface of the holders 4 and 5.
The holders 4 and 5 may be formed in arc shapes, and the X-ray generator 1 may be provided so as to be slidable along the arcs of the holders 4 and 5.
The holders 4 and 5 may be supported rotatably by a supporting base 4. Further, the holders 4 and 5 may be supported by the supporting base 6 so as to be slidable along the arcs of the holders 4 and 5.
The supporting base 6 may be provided movably.
The holders may not be two, but only one holder may be provided like a holder 20 shown in FIG. 10. Alternatively, the holder may be structured by a first holder 4,formed in an arc shape, for movably holding the X-ray generator, and a second holder 5 for supporting the first holder slidably along the arc of the first holder.
The X-ray detector 2 may be structured by a planar detector formed by a two-dimensional array of a plurality of X-ray detecting elements for converting X-rays transmitted through the subject into charge signals and for storing the charge signals.
The X-ray detector 2 may be held by the arm 3 in such a way as to be able to change a distance from the X-ray detector 2 to the X-ray generator 1. Further, the X-ray detector 2 may be held by the arm 3 rotatably around an X-ray axis formed by a line connecting between the X-ray generator 1 and the X-ray detector 2. Further, the X-ray detector 2 may also be held by the arm 3 so that an angle formed by the X-ray detector 2 and the X-ray generator 1 can be changed.
A second aspect of the invention provides, an X-ray diagnostic imaging apparatus for irradiating X-rays onto a subject under examination and picking up an image of the subject by detecting the X-rays transmitted through the subject, the X-ray diagnostic imaging apparatus comprising: an X-ray generator 1 for irradiating X-rays onto the subject; an X-ray detector 2 for taking in an X-ray image formed by the X-rays irradiated onto the subject and transmitted through the subject, the X-ray detector 2 being structured by a two-dimensional array of a plurality of X-ray detecting elements for converting X-rays transmitted through the subject into charge signals and for storing the charge signals; an arm 3 extended from the X-ray generator 1 to make a detour around the subject, for fixedly holding the X-ray detector 2; and at least one holder 4 and 5 for holding the X-ray generator 1 so that the X-ray generator 1 can rotate and/or slide along the holder.
According to the above-described structure, the X-ray generator 1 is provided rotatably or slidably along the holder 4, and the holder 5 is supported movably or slidably by the supporting base 6. Further, the holder is structured by the first holder 4 and the second holder 5 that can slide along each other, and the X-ray detector 2 is provided movably in forward and backward directions or is tilted. With this structure, making an access to the subject can be improved, and the operation of the operator can also be improved. Thus, it becomes possible to collect images of the subject over a wider range of the body.
Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.